| /* |
| * Copyright (c) 2011-2013, 2015 ARM Limited |
| * All rights reserved |
| * |
| * The license below extends only to copyright in the software and shall |
| * not be construed as granting a license to any other intellectual |
| * property including but not limited to intellectual property relating |
| * to a hardware implementation of the functionality of the software |
| * licensed hereunder. You may use the software subject to the license |
| * terms below provided that you ensure that this notice is replicated |
| * unmodified and in its entirety in all distributions of the software, |
| * modified or unmodified, in source code or in binary form. |
| * |
| * Copyright (c) 2006 The Regents of The University of Michigan |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are |
| * met: redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer; |
| * redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution; |
| * neither the name of the copyright holders nor the names of its |
| * contributors may be used to endorse or promote products derived from |
| * this software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| /** |
| * @file |
| * Implementation of a memory-mapped bridge that connects a requestor |
| * and a responder through a request and response queue. |
| */ |
| |
| #include "mem/bridge.hh" |
| |
| #include "base/trace.hh" |
| #include "debug/Bridge.hh" |
| #include "params/Bridge.hh" |
| |
| namespace gem5 |
| { |
| |
| Bridge::BridgeResponsePort::BridgeResponsePort(const std::string& _name, |
| Bridge& _bridge, |
| BridgeRequestPort& _memSidePort, |
| Cycles _delay, int _resp_limit, |
| std::vector<AddrRange> _ranges) |
| : ResponsePort(_name, &_bridge), bridge(_bridge), |
| memSidePort(_memSidePort), delay(_delay), |
| ranges(_ranges.begin(), _ranges.end()), |
| outstandingResponses(0), retryReq(false), respQueueLimit(_resp_limit), |
| sendEvent([this]{ trySendTiming(); }, _name) |
| { |
| } |
| |
| Bridge::BridgeRequestPort::BridgeRequestPort(const std::string& _name, |
| Bridge& _bridge, |
| BridgeResponsePort& _cpuSidePort, |
| Cycles _delay, int _req_limit) |
| : RequestPort(_name, &_bridge), bridge(_bridge), |
| cpuSidePort(_cpuSidePort), |
| delay(_delay), reqQueueLimit(_req_limit), |
| sendEvent([this]{ trySendTiming(); }, _name) |
| { |
| } |
| |
| Bridge::Bridge(const Params &p) |
| : ClockedObject(p), |
| cpuSidePort(p.name + ".cpu_side_port", *this, memSidePort, |
| ticksToCycles(p.delay), p.resp_size, p.ranges), |
| memSidePort(p.name + ".mem_side_port", *this, cpuSidePort, |
| ticksToCycles(p.delay), p.req_size) |
| { |
| } |
| |
| Port & |
| Bridge::getPort(const std::string &if_name, PortID idx) |
| { |
| if (if_name == "mem_side_port") |
| return memSidePort; |
| else if (if_name == "cpu_side_port") |
| return cpuSidePort; |
| else |
| // pass it along to our super class |
| return ClockedObject::getPort(if_name, idx); |
| } |
| |
| void |
| Bridge::init() |
| { |
| // make sure both sides are connected and have the same block size |
| if (!cpuSidePort.isConnected() || !memSidePort.isConnected()) |
| fatal("Both ports of a bridge must be connected.\n"); |
| |
| // notify the request side of our address ranges |
| cpuSidePort.sendRangeChange(); |
| } |
| |
| bool |
| Bridge::BridgeResponsePort::respQueueFull() const |
| { |
| return outstandingResponses == respQueueLimit; |
| } |
| |
| bool |
| Bridge::BridgeRequestPort::reqQueueFull() const |
| { |
| return transmitList.size() == reqQueueLimit; |
| } |
| |
| bool |
| Bridge::BridgeRequestPort::recvTimingResp(PacketPtr pkt) |
| { |
| // all checks are done when the request is accepted on the response |
| // side, so we are guaranteed to have space for the response |
| DPRINTF(Bridge, "recvTimingResp: %s addr 0x%x\n", |
| pkt->cmdString(), pkt->getAddr()); |
| |
| DPRINTF(Bridge, "Request queue size: %d\n", transmitList.size()); |
| |
| // technically the packet only reaches us after the header delay, |
| // and typically we also need to deserialise any payload (unless |
| // the two sides of the bridge are synchronous) |
| Tick receive_delay = pkt->headerDelay + pkt->payloadDelay; |
| pkt->headerDelay = pkt->payloadDelay = 0; |
| |
| cpuSidePort.schedTimingResp(pkt, bridge.clockEdge(delay) + |
| receive_delay); |
| |
| return true; |
| } |
| |
| bool |
| Bridge::BridgeResponsePort::recvTimingReq(PacketPtr pkt) |
| { |
| DPRINTF(Bridge, "recvTimingReq: %s addr 0x%x\n", |
| pkt->cmdString(), pkt->getAddr()); |
| |
| panic_if(pkt->cacheResponding(), "Should not see packets where cache " |
| "is responding"); |
| |
| // we should not get a new request after committing to retry the |
| // current one, but unfortunately the CPU violates this rule, so |
| // simply ignore it for now |
| if (retryReq) |
| return false; |
| |
| DPRINTF(Bridge, "Response queue size: %d outresp: %d\n", |
| transmitList.size(), outstandingResponses); |
| |
| // if the request queue is full then there is no hope |
| if (memSidePort.reqQueueFull()) { |
| DPRINTF(Bridge, "Request queue full\n"); |
| retryReq = true; |
| } else { |
| // look at the response queue if we expect to see a response |
| bool expects_response = pkt->needsResponse(); |
| if (expects_response) { |
| if (respQueueFull()) { |
| DPRINTF(Bridge, "Response queue full\n"); |
| retryReq = true; |
| } else { |
| // ok to send the request with space for the response |
| DPRINTF(Bridge, "Reserving space for response\n"); |
| assert(outstandingResponses != respQueueLimit); |
| ++outstandingResponses; |
| |
| // no need to set retryReq to false as this is already the |
| // case |
| } |
| } |
| |
| if (!retryReq) { |
| // technically the packet only reaches us after the header |
| // delay, and typically we also need to deserialise any |
| // payload (unless the two sides of the bridge are |
| // synchronous) |
| Tick receive_delay = pkt->headerDelay + pkt->payloadDelay; |
| pkt->headerDelay = pkt->payloadDelay = 0; |
| |
| memSidePort.schedTimingReq(pkt, bridge.clockEdge(delay) + |
| receive_delay); |
| } |
| } |
| |
| // remember that we are now stalling a packet and that we have to |
| // tell the sending requestor to retry once space becomes available, |
| // we make no distinction whether the stalling is due to the |
| // request queue or response queue being full |
| return !retryReq; |
| } |
| |
| void |
| Bridge::BridgeResponsePort::retryStalledReq() |
| { |
| if (retryReq) { |
| DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); |
| retryReq = false; |
| sendRetryReq(); |
| } |
| } |
| |
| void |
| Bridge::BridgeRequestPort::schedTimingReq(PacketPtr pkt, Tick when) |
| { |
| // If we're about to put this packet at the head of the queue, we |
| // need to schedule an event to do the transmit. Otherwise there |
| // should already be an event scheduled for sending the head |
| // packet. |
| if (transmitList.empty()) { |
| bridge.schedule(sendEvent, when); |
| } |
| |
| assert(transmitList.size() != reqQueueLimit); |
| |
| transmitList.emplace_back(pkt, when); |
| } |
| |
| |
| void |
| Bridge::BridgeResponsePort::schedTimingResp(PacketPtr pkt, Tick when) |
| { |
| // If we're about to put this packet at the head of the queue, we |
| // need to schedule an event to do the transmit. Otherwise there |
| // should already be an event scheduled for sending the head |
| // packet. |
| if (transmitList.empty()) { |
| bridge.schedule(sendEvent, when); |
| } |
| |
| transmitList.emplace_back(pkt, when); |
| } |
| |
| void |
| Bridge::BridgeRequestPort::trySendTiming() |
| { |
| assert(!transmitList.empty()); |
| |
| DeferredPacket req = transmitList.front(); |
| |
| assert(req.tick <= curTick()); |
| |
| PacketPtr pkt = req.pkt; |
| |
| DPRINTF(Bridge, "trySend request addr 0x%x, queue size %d\n", |
| pkt->getAddr(), transmitList.size()); |
| |
| if (sendTimingReq(pkt)) { |
| // send successful |
| transmitList.pop_front(); |
| DPRINTF(Bridge, "trySend request successful\n"); |
| |
| // If there are more packets to send, schedule event to try again. |
| if (!transmitList.empty()) { |
| DeferredPacket next_req = transmitList.front(); |
| DPRINTF(Bridge, "Scheduling next send\n"); |
| bridge.schedule(sendEvent, std::max(next_req.tick, |
| bridge.clockEdge())); |
| } |
| |
| // if we have stalled a request due to a full request queue, |
| // then send a retry at this point, also note that if the |
| // request we stalled was waiting for the response queue |
| // rather than the request queue we might stall it again |
| cpuSidePort.retryStalledReq(); |
| } |
| |
| // if the send failed, then we try again once we receive a retry, |
| // and therefore there is no need to take any action |
| } |
| |
| void |
| Bridge::BridgeResponsePort::trySendTiming() |
| { |
| assert(!transmitList.empty()); |
| |
| DeferredPacket resp = transmitList.front(); |
| |
| assert(resp.tick <= curTick()); |
| |
| PacketPtr pkt = resp.pkt; |
| |
| DPRINTF(Bridge, "trySend response addr 0x%x, outstanding %d\n", |
| pkt->getAddr(), outstandingResponses); |
| |
| if (sendTimingResp(pkt)) { |
| // send successful |
| transmitList.pop_front(); |
| DPRINTF(Bridge, "trySend response successful\n"); |
| |
| assert(outstandingResponses != 0); |
| --outstandingResponses; |
| |
| // If there are more packets to send, schedule event to try again. |
| if (!transmitList.empty()) { |
| DeferredPacket next_resp = transmitList.front(); |
| DPRINTF(Bridge, "Scheduling next send\n"); |
| bridge.schedule(sendEvent, std::max(next_resp.tick, |
| bridge.clockEdge())); |
| } |
| |
| // if there is space in the request queue and we were stalling |
| // a request, it will definitely be possible to accept it now |
| // since there is guaranteed space in the response queue |
| if (!memSidePort.reqQueueFull() && retryReq) { |
| DPRINTF(Bridge, "Request waiting for retry, now retrying\n"); |
| retryReq = false; |
| sendRetryReq(); |
| } |
| } |
| |
| // if the send failed, then we try again once we receive a retry, |
| // and therefore there is no need to take any action |
| } |
| |
| void |
| Bridge::BridgeRequestPort::recvReqRetry() |
| { |
| trySendTiming(); |
| } |
| |
| void |
| Bridge::BridgeResponsePort::recvRespRetry() |
| { |
| trySendTiming(); |
| } |
| |
| Tick |
| Bridge::BridgeResponsePort::recvAtomic(PacketPtr pkt) |
| { |
| panic_if(pkt->cacheResponding(), "Should not see packets where cache " |
| "is responding"); |
| |
| return delay * bridge.clockPeriod() + memSidePort.sendAtomic(pkt); |
| } |
| |
| void |
| Bridge::BridgeResponsePort::recvFunctional(PacketPtr pkt) |
| { |
| pkt->pushLabel(name()); |
| |
| // check the response queue |
| for (auto i = transmitList.begin(); i != transmitList.end(); ++i) { |
| if (pkt->trySatisfyFunctional((*i).pkt)) { |
| pkt->makeResponse(); |
| return; |
| } |
| } |
| |
| // also check the request port's request queue |
| if (memSidePort.trySatisfyFunctional(pkt)) { |
| return; |
| } |
| |
| pkt->popLabel(); |
| |
| // fall through if pkt still not satisfied |
| memSidePort.sendFunctional(pkt); |
| } |
| |
| bool |
| Bridge::BridgeRequestPort::trySatisfyFunctional(PacketPtr pkt) |
| { |
| bool found = false; |
| auto i = transmitList.begin(); |
| |
| while (i != transmitList.end() && !found) { |
| if (pkt->trySatisfyFunctional((*i).pkt)) { |
| pkt->makeResponse(); |
| found = true; |
| } |
| ++i; |
| } |
| |
| return found; |
| } |
| |
| AddrRangeList |
| Bridge::BridgeResponsePort::getAddrRanges() const |
| { |
| return ranges; |
| } |
| |
| } // namespace gem5 |
